1. Field of the Invention
The present invention relates to a flat panel display and a method of manufacturing a flat panel display, and more particularly, to sealed, flexible flat panel display and a method of manufacturing the sealed, flexible flat panel display.
2. Discussion of the Background
Generally, flat panel displays (FPDs), such as organic light emitting displays (OLEDs), thin film transistor liquid crystal displays (TFT-LCD), etc., have characteristics allowing them to be made thin and flexible. Accordingly, much research is being conducted into thin, flexible FPDs.
A flexible substrate is used to produce thin, flexible FPDs, and a plastic substrate is often used as the flexible substrate.
However, because FPDs undergo complicated fabrication processes, such as forming an organic film, a thin film transistor layer, an electrode layer, an orientation layer, etc., on a substrate, depending on the FPD's particular characteristics, when using a plastic substrate, such processes may deform the plastic substrate or the thin layers formed on the plastic substrate. Also, plastic is generally less dense than glass.
Furthermore, a plastic substrate may not effectively prevent permeation of water or air.
To solve this problem, a plastic substrate may be coated with a barrier layer to block permeation of water or air.
For example, U.S. Pat. Nos. 6,268,695 and 6,497,598 disclose an organic light emitting device encapsulated in a film including polymer layers and a ceramic layer interposed between the polymer layers. U.S. Pat. No. 6,413,645 discloses an organic light emitting device encapsulated in a stack of at least one polymer layer and at least one inorganic layer. U.S. Pat. No. 6,522,067 discloses an organic light emitting device encapsulated in a stack of at least one barrier and at least one polymer layer. U.S. Pat. No. 6,548,912 discloses a micro-electronic device encapsulated in a stack of at least one barrier layer and at least one polymer layer. U.S. Pat. No. 6,570,325 discloses an organic light emitting device encapsulated in a stack where a barrier layer is interposed between decoupling layers. U.S. Pat. No. 6,573,652 discloses a display device encapsulated in a stack of at least one barrier layer and at least one polymer layer.
However, when using such a barrier layer, which includes an inorganic film, to encapsulate an FPD, the barrier layer may be too thin, which may degrade its durability. Even when the barrier layer is formed on a flexible plastic substrate, the limit of a process temperature is low, so manufacturing an FPD may be difficult.
Thus, there is room for improvement in sealing display devices for flexible FPDs.
Korean Patent Publication No. 2003-2946 discloses an organic light emitting device sealed by plastic that is heated and press-fitted onto the light emitting device instead of being adhered by an adhesive. In this case, although sealing may be simply performed, the plastic may not completely prevent permeation of water and air. This results in degradation of the lifespan and durability of the organic light emitting device.
U.S. Patent Publication No. 2003/0027369 A1 discloses a method of making a light emitting device that is vacuum-sealed with a bag-like plastic film inside of which inorganic insulating films, which may prevent oxygen or water from penetrating therein, and an organic insulating film, which has a smaller internal stress than the inorganic insulating films, are laminated. However, when the plastic film having the inorganic insulative film bends, the inorganic insulative film may crack, leading to degradation of the ability of preventing permeation of water and air.
Japanese Patent Publication No. 1993-144569 discloses a method of manufacturing a light emitting device that is sealed by forming a thermoplastic hygroscopic film on both sides of the light emitting device, heating and press-fitting the film onto the light emitting device to seal the device's peripheral parts, and then covering the sealed light emitting device with an outer cover film. However, the thermoplastic hygroscopic film and the outer cover film may not completely prevent permeation of water and air.